Deductions & credits

I think my question is different as I don’t have any points.

below are my questions as I have three 1098 forms.

1. I have to combine all three 1098 form mortgage interest (box 1) and enter as single entry, please confirm 

2. I have three 1098 forms . I have to enter outstanding mortgage principal (box 2) and mortgage orientation date (box 3) from which 1098 form ? First 1098 form or third 1098 form?